Robo-Lizard

As I mentioned in my last project Sixteen-pede, I am fascinated by the small animals that get along with little "program" and/or energy.

For this robotic lizard I use only 3 servos. Two for the leg movements and one for the rotation of the body, so that the friction of the legs on the ground can act at the right moment. A Wemos D1 mini (ESP8266) forms the brain; via WiFi we will control the lizard remotely. Optionally, you could also mount a sensor and let the robot decide the direction itself.

We remove the mounting tabs on the servos so we can glue them together in a better way. The servos front and center are glued together. From plywood (or craft plastic) we saw a small platform on which the ESP8266 will fit.

We glue the rear servo together with the battery holder. We put the rear plywood platform on the servo and glue the mount, servo and platform together.

It would be good to connect the middle servo to a Wemos D1 already to set it to center (90).

I bent the servo arm for the middle servo a little with the help of the hot soldering iron, so that it "grips" the battery holder. We mount this servo arm to the servo with the corresponding screw, then we glue the whole thing to the battery holder.

The body is now almost finished.

I use a 18650 LiPo battery and a LiPo charging circuit. It is smaller and lighter than a power bank and provides a full 5V for Wemos and servos despite the 3.7V of the battery. The 18650 does not need to be replaced, you can charge the Lizard via the USB port on the rear end.

[Design using TinkerCAD]

Separate the servo cables into individual cables.

Connect the plus (red) and minus (black) of the battery to the charging module, middle contacts B = battery.

Attention: A slide switch should be added to the plus cable. Later we glue the switch between the servo and the charging module with a few pieces of wood.

From the charger module we connect the motors and the Esp8266 with a parallel circuit. We connect the outer loading module contacts + and - with +(red) and - (brown) of the rear servo. From here we connect the middle servo and from this again the front servo. Finally we connect the ESP8266 to GND and 5V.

We solder the data lines (orange) of the motors directly to the Wemos.

front --> D7 (14)

middle --> D6 (12)

rear --> D5 (13)

After that you can glue all loose cables a little bit to the body.

Now you can upload the file robo-lizard.ino to the Wemos and try out the 'animal' for the first time.

You can find good instructions for uploading to Wemos D1 here:

https://www.instructables.com/Nodemcu-Mini-D1-R1-for-Beginner-ESP8266-Bink-Wemos/

When you start the robo-lizard, all servos first go into the center starting position (90) for 2 seconds, than it is ready and awaiting your commands.

Download the app "RemoteXY: Arduino control" (it's free!) from GooglePlay or other shops and install it on your smartphone.

Power up your Wemos D1, start the app on your smartphone and you see an empty panel.

• Press "+" to add a new connection.
• Press "Wi-Fi point"
• Choose "RemoteXY" from the list.
• Enter password "1234567890" - not very fancy, I know

Now you can use the remote control for your robo-lizard. Stop! Mount the legs first.

Thread wire through double servo arms as shown in the picture. Cut the wire legs on each side to exactly the same length (approx. 6 cm + 1cm).

Fold the last centimeter of the wire to make a foot.

Cut four10 mm long pieces of heat shrink tubing and put them over the feet, the tube must protrude a little. Shrink the tube with the hot soldering iron.

Mount the legs to the servos, check that the legs are the same length and shape on each side.

You could tilt the middle servo more to lift the legs a little higher.

I use a couple of green balloons for the skin. I pull them over the headboard and the torso like socks. In the middle part I leave a little gap free so that the body can twist.

Then gently cut out the servo arm connectors and remount the legs. In addition, the balloon skin gives more stability. The lizard can be charged at the rear via USB.

You think, your lizard needs some more decoration, e.g. eyes? Go ahead...!

Switch on and

have fun with your robo-lizard!